The present disclosure relates to de-icing systems for an aircraft, and more specifically, to resistive-inductive de-icing systems for aircraft flight control surfaces.
Icing of aircraft flight control surfaces during adverse ambient flight conditions is a well-known aerodynamic problem. Ice formation and accumulation on flight control surfaces may cause the performance of the component and/or system to be degraded. In addition, the shearing of accumulated ice may cause damage to aircraft components in the downstream path of the flying ice. Additional damage to “runback” where melted ice water travels along the de-iced surface and subsequently re-freezes on the un-heated portions of the de-iced surface are also very serious. Such damages may incapacitate various aircraft flight control systems and could, in the extreme case, lead to a catastrophic aircraft damage causing loss of property and life. Hence, the proposed de-icing system can be configured to be either “running wet” (i.e., just enough heat is supplied to the de-iced surface to convert ice to liquid water) or “running dry” (i.e., enough heat is supplied to the de-iced surface to convert ice to water vapor). Both configurations are plausible and can be supported by the proposed de-icing system. However, in order to avoid any “runback”-related problems, it may be beneficial to design the de-icing system in a “run dry” configuration.
One common method for preventing icing on aerodynamic control surfaces is the application of various anti-icing fluids to create a shield coating over the protected aerodynamic control surface. The fluid is designed to not allow ice formation and to aid in repelling any accumulated ice and/or snow.
Other de-icing approaches that have been developed include in-flight de-icing for both moving parts as well as fixed aerodynamic surfaces. Some of the most widely used methods for de-icing flight control surfaces are based on electrical resistive heating or pneumatic heating using hot pressurized air bleed from a predetermined compressor stage of the aircraft engines. Existing pneumatic systems result in a direct parasitic loss on the thermodynamic performance of the engines. Due to the desire to minimize weight associated with plumbing and valves required by pneumatic systems, the flight control surfaces that are heated are typically limited to the surfaces located in the vicinity of the hot air bleed source, i.e. the main engines. In most modern civil aircraft configurations this means that the wings' leading edges will be heated (due to the proximity to the pod-style under-wing suspended engines) but other critical flight surfaces such as the leading edge of the vertical stabilizer (fin), or the horizontal stabilizers, or the nose cone of the aircraft fuselage may not be heated.